1. Field of the Invention
The present invention relates to a seat slide structure for a vehicle, such as an automobile.
2. Description of the Related Art
Heretofore, there has been proposed a seat slide structure for a vehicle, as disclosed, for example, in JP 2004-106713A. A seat slide structure disclosed in this publication comprises a screw rod (threaded rod) non-rotatably fixed to a lower rail, and a nut member screwed with the screw rod. A holding member is fixed to the upper rail. The holding member is formed by subjecting a plate-shaped body to bending. The holding member includes a front holding piece, a rear holding piece, and a connection piece connecting between respective base ends of the front and rear holding pieces, and has a U shape.
The nut member is rotatably supported by a gearbox. The gearbox is installed between the front and rear holding pieces of the holding member. In other words, the nut member is held by the holding member through the gearbox (see FIG. 4 in the JP 2004-106713A).
When the nut member is rotated and moved along an axial direction of the screw rod, the nut member presses the holding member frontwardly or rearwardly through the gearbox. Thus, the upper rail is moved frontwardly or rearwardly with respect to the lower rail.
However, the holding member having a U shape involves the following problem. For example, as shown in FIG. 28, when a frontward or rearward force P is applied to an upper rail 100 (FIG. 28 illustrates an example where a rearward force is applied thereto), a holding member 101 is urged to be moved in the direction of the force P together with the upper rail 100, so that it presses a gearbox 102. The gearbox 102 receiving the force P presses a nut member 103. However, the pressed nut member 103 cannot be moved because it is screwed with a screw rod 104. Thus, the gearbox 102 and the holding member 101 receive a reaction force from the nut member 103. The reaction force is likely to cause deformation of the holding member 101, as shown in FIG. 28.
As means for suppressing such deformation, for example, it is contemplated to increase a plate thickness of each of the gearbox 102 and the holding member 101. However, in this case, due to an increase in force required for bending, it becomes difficult to adequately form the gearbox 102 and the holding member 101. Moreover, due to an increase in size of the holding member, it becomes difficult to install the holding member in the upper or lower rail.